In recent years, in the “cdma2000 1x-EV DO standard,” a protocol (3G1X protocol: 3G1X Circuit Service Notification Protocol) has been developed. The protocol prescribes that a mobile terminal receives a paging message of a 1x network (circuit switching network) using a control channel or a traffic channel that is set for an EV-DO base station (packet switching network base station).
FIG. 1 shows an outline of a mobile communication system in which a mobile terminal MS can communicate using the 3G1X protocol.
Hereinafter, with reference to FIGS. 2 and 3, operation will be described in which the paging message of the 1x network is received while the 3G1X protocol is used, and subsequently, a received call processing in the 1x network is performed in this mobile communication system.
As shown in FIG. 2, at Step S1001, the mobile terminal MS receives broadcast information from a 1x base station BS#1, the broadcast information including a base station ID that identifies the 1x base station BS#1 and a network ID that identifies a mobile switching center MSC#1 connected to the 1x base station BS#1.
At Step S1002, the mobile terminal MS transmits a “3G1X protocol use request” for requesting start of use of the 3G1X protocol to an EV-DO base station BS#1 that is performing a location registration processing.
At Step S1003, in response to the received “3G1X protocol use request,” the EV-DO base station BS#1 transmits a “3G1X protocol use approval” for approving start of use of the 3G1X protocol to the mobile terminal MS.
At Step S1004, the mobile terminal MS starts using the 3G1X protocol in response to the received “3G1X protocol use approval,” and transmits, to the EV-DO base station BS#1, a “3G1X Service Packet (DO packet including a signaling message of the 1x network)” for informing the 1x base station BS#1 of a location registration request for performing a location registration processing.
The mobile terminal MS is configured not to receive a radio signal from the 1x network while using the 3G1X protocol.
At Step S1005, the EV-DO base station BS#1 transmits, to the mobile terminal MS, a “3G1X Service Packet” for informing the 1x base station BS#1 of a location registration completion response indicating that the location registration processing is completed.
At Step S1006, through a 1x higher order switching center GMSC, an EV-DO higher node PDSN, and a packet control function PCF#1, the EV-DO base station BS#1 is informed of a received call addressed to the mobile terminal MS from an originating terminal through the 1x network. Then the EV-DO base station BS#1 transmits, to the mobile terminal MS, the “3G1X Service Packet” for informing the mobile terminal MS of a paging message addressed to the mobile terminal MS.
Here, the paging message addressed to the mobile terminal MS notifies that there is a received call addressed to the mobile terminal MS from an originating terminal through the 1x network.
At Step S1007, the mobile terminal MS transmits a “3G1X protocol stop request” for requesting stop of use of the 3G1X protocol, to the EV-DO base station BS#1.
At Step S1008, the EV-DO base station BS#1 transmits a “3G1X protocol stop approval” for approving stop of use of the 3G1X protocol to the mobile terminal MS in response to the received “3G1X protocol stop request.”
At Step S1009, by receiving broadcast information from a 1x base station BS, the mobile terminal MS confirms BS under which 1x base station the mobile terminal MS is located at present.
At Step S1010, the 1x base stations S#1 and #2 under the mobile switching center MSC#1 inform the mobile terminal MS of the paging message addressed to the mobile terminal MS from the originating terminal through the 1x network.
At Step S1011, the mobile terminal MS determines that the mobile terminal MS has not fallen under the necessity for “1x handoff processing” while using the 3G1X protocol (Step S1004 to S1008), because the base station ID (1x base station BS#1) included in the broadcast information received by the mobile terminal MS at Step S1009 is not changed. Then, in response to the paging massage informed by the 1x base station BS#1 at Step S1010 and received by the mobile terminal MS from the 1x base station BS#1, the mobile terminal MS starts communication with the originating terminal through the 1x network.
Next, with reference to FIGS. 4 and 5, operation will be described for the case where the mobile terminal MS is moved into a cover area of another different 1x base station BS under the same mobile switching center MSC while using the 3G1X protocol, that is, where the base station ID included in the broadcast information received in the mobile terminal MS after the 3G1X protocol is stopped is changed into the base station ID of the different 1x base Station BS under the same mobile switching center MSC.
As shown in FIG. 4, operation from Step S2001 to S2010 is the same as the above-mentioned operation from Step S1001 to S1010.
At Step S2011, the mobile terminal MS determines that the mobile terminal MS is moved into the cover area of a different 1x base station BS under the same mobile switching center MSC#1 white using the 3G1X protocol (Step S2004 to S2008), because the base station ID (1x base station BS#1) included in the broadcast information received by the mobile terminal MS at Step S2009 is changed into another base station ID (1x base station BS#2) of the different 1x base station under the same mobile switching center MSC#1. Then, in response to the paging message informed by the 1x base station BS#2 at Step S2010 and received by the mobile station MS from the 1x base station BS#2, the mobile terminal MS to starts the communication with the originating terminal through the 1x network.
Furthermore, with reference to FIGS. 6 and 7, operation will be described for the case where the mobile terminal MS has fallen under the necessity for “1x handoff processing” between 1x base stations BS under different mobile switching centers MSC while using the 3G1X protocol, that is, where the base station ID included in the broadcast information received in the mobile terminal MS after the 3G1X protocol is stopped is changed into the base station ID of the 1x base station BS under the different mobile switching center.
As shown in FIG. 6, operation from Step S3001 to S3009 is the same as the above-mentioned operation from Step S1001 to S1009.
At Step S3010, the mobile terminal MS determines that the mobile terminal MS has fallen under the necessity for “1x handoff processing” between the 1x base station BS#1 and BS#3 under different mobile switching centers MSC#1 and MSC#2 while using the 3G1X protocol (step S3004 to S3008), because the base station ID (1x base station BS#1) included in the broadcast information received by the mobile terminal MS at Step S3009 is changed into the base station ID (1x base station BS#3) of the 1x base station under the different mobile switching center MSC#2.
Here, the 1x base stations BS#1 and BS#2 under the mobile switching center MSC#1 inform the mobile terminal MS of the paging message addressed to the mobile terminal MS from the originating terminal through the 1x network. Therefore, under this condition, the mobile terminal MS cannot receive the paging message addressed to the mobile terminal MS, and cannot start the communication with the originating terminal through the 1x network. Then, the mobile terminal MS transmits a location registration request to the 1x base station BS#3.
At Step S3011, the 1x base station BS#3 performs the location registration processing for the mobile terminal MS in response to the received location registration request, and to the mobile terminal MS, transmits a location registration completion response for informing that the location registration processing is completed.
At Step S3012, after completion of the location registration processing of the mobile terminal MS, the 1x base station BS#3 under the mobile switching center MSC#2 starts notification of the paging message addressed to the mobile terminal MS from the originating terminal through the ax network. At Step S3013, the mobile terminal MS starts the communication with the originating terminal through the 1x network in response to the paging message received from the 1x base station BS#3.
Nonpatent literature 1: “cdma2000 High Rate Packet Data Air Interface 3GPP2 C.S0024 Version 4.0,” 3GPP2, October, 2002 (Section 8.5.6.1, Section 9.3.1.3.2.3.2)
Nonpatent literature 2: “cdma2000 High Rate Packet Data Air Interface 3GPP2 C.S0024-A Version 1.0,” 3GPP2, March, 2004 (Section 14.2.1.3.1.1, Section 14.3.1.3.1.1)